This invention relates to a conveyor system, and in particular to an accumulating conveyor for use inside a vehicle.
In order to transport large articles such as car seats, it is known to position one or more of the articles on a pallet, and to feed the pallet into a vehicle such as the trailer of an articulated lorry using a conveyor positioned on the floor of the trailer. Typically, an accumulating conveyor is used, so that pallets can be fed into the trailer in succession so that, when a given pallet is fed into the trailer as far as it can travel, that pallet will maintain its position whilst the conveyor continues to feed further pallets into the trailer. Typically, an accumulating conveyor has one or more endless chains, the links of which carry freely-rotatable rollers. In use, a pallet is positioned on the conveyor at the rear of the trailer, and the conveyor chain drive is engaged to carry the pallet into the trailer. When that pallet reaches the front of the trailer, where it is prevented from further movement, the rollers supporting that pallet rotate backwards whilst the chain or chains are driven further forward. Consequently, one or more further pallets can be fed into the trailer from its rear, each of the additional pallets, in turn, being fed into the trailer until it engages with a stationary pallet immediately adjacent thereto towards the front of the trailer. In this way, pallets can continue to be fed into the interior of the trailer by continuously driving the conveyor drive chain or chains, without risk of the pallets or the articles they carry being damaged by collisions therebetween.
A known conveyor system of this type has a central drive chain and a pair of sets of rollers positioned on opposite sides thereof. The central chain is positioned within an elongate recessed portion of the trailer floor, and each of the sets of rollers is similarly positioned in a respective elongate recessed portion of the trailer floor, the three recessed portions extending longitudinally along the floor of the trailer. A respective airbag is positioned on the base of each of the recessed portions, so that the airbags can support the sets of rollers and the drive chain. In use, the airbags are inflated to lift the drive chain and the rollers slightly above the trailer floor. Pallets can then be fed into the trailer by engaging the drive of the chain. As soon as all the pallets are positioned, the airbags are deflated, and the pallets drop down to rest on the floor of the trailer. Frictional contact between the pallets and the trailer floor will subsequently tend to prevent movement of the pallets relative to the floor as the trailer moves, particularly when it accelerates or is braked.
The disadvantage of this known system is that an air supply to the bags is required throughout loading and unloading operations, which means that the tractor unit of the vehicle must be connected to the trailer during loading or unloading, or a separate air supply is required. Another disadvantage of this known system is that, if the products supported by the pallets are light, the frictional force between the pallets and the vehicle floor may be insufficient to stop the pallets moving if the vehicle accelerates or brakes abruptly, or if it travels over a bumpy road.